Rare Bird Threatened by San Diego Bay National Wildlife Refuge
Population Control Proposal

PORTLAND, Oreg.— Today the Center for Biological Diversity filed a scientific petition with the U.S. Fish and Wildlife Service to protect the western gull-billed tern as an endangered species under the federal Endangered Species Act. The western gull-billed tern has only two breeding sites in the United States. At one of them, San Diego Bay National Wildlife Refuge, it is immediately threatened by a Fish and Wildlife Service plan to reduce its population by destroying eggs. The control effort is intended to protect two other endangered seabirds: the western snowy plover and the California least tern.

“The Center strongly supports the conservation of all three of these endangered birds,” said Tierra Curry, a conservation biologist with the Center for Biological Diversity. “The western gull-billed tern is endangered and needs the same protections afforded the plover and least tern.”

In the United States and Mexico, there are roughly 1,000 to 2,000 western gull-billed terns, 5,000 snowy plovers, and 14,000 California least terns. On the Bay Refuge, there are roughly 100 adult gull-billed terns, four adult plovers, and 160 adult least terns. Western gull-billed terns do prey on plover and least tern chicks, but they are not the only threat facing these species and they themselves are highly endangered.

“With only four adults, we understand the concern for this very small population of western snowy plovers and we are actively engaged in rangewide efforts to protect this highly endangered species,” said Curry. “We acknowledge the impact of predation on the refuge; the real problem for the plover and both the tern species, however, is habitat destruction.”

The Refuge proposes to destroy all of the eggs in more than 40 percent of the gull-billed terns’ nests by coating them in corn oil or by other methods. The western gull-billed tern is less abundant, and has fewer breeding sites, than the two listed endangered seabird species, and does not pose a significant rangewide threat to either of them. “It is the job of Fish and Wildlife Service to protect this rare tern, not to push it closer to extinction,” said Curry.

Other threats to the gull-billed tern include falling water levels and pollution at the Salton Sea, predation, human intrusion at nesting locations, and the killing of adults to prevent collisions with naval aircraft in San Diego Bay. In Mexico, where the western gull-billed tern has 12 breeding sites, it is threatened by habitat development and disturbance, flooding, and the killing of foraging adults at commercial shrimp farms. The western gull-billed tern is a stout, white, medium-sized, black-capped seabird with a black bill and black legs and feet.

The U.S. Fish and Wildlife Service has 90 days to determine whether the petition presents substantial scientific information to warrant Endangered Species Act protection for the western gull-billed tern, and one year to determine if the bird warrants protection as an endangered subspecies.